Exciting adventures on the farm await the Bobbsey twins as they arrive at Meadowbrook station. Uncle Daniel, who comes to meet them, is going to deliver a little bear cub, Arthur, to a friend, while Cousin Harry tells about several bank robberies in the neighborhood.

Nan, Bert, Freddie, and Flossi's detective skill is needed when Arthur disappears from the animal farm. Then the children spot an old green car like the one the bank robbers use, and Cousin Harry's homing pigeon returns with a mysterious message.

Discovery of a cabin in the woods and the disappearance of all the animals from the miniature zoo are puzzling links in the mystery chain.

But the children enjoy an overnight camping trip, a happy ride in an old river barge, the exciting homing pigeon race, and the "big game" hunt in which Freedie catches a mouse!

Actually, it's the homing pigeons who furnish the little detectives with the big clue to the solution of all the queer events. And the last mystery - what to do with the reward - has a surprising ending too.

In this book of the Bobbsey twins, the kids take a trip to see their aunt, uncle, and cousin Harry. But adventure awaits them there, two thieves are reported to be robbing banks. The children chase the robbers, win money,and have great fun.